1. Field of the Invention
The present invention relates to a force sensor unit. In particular, this invention relates to a force sensor unit in which the effects of temperature changes are excluded when an external force is applied thereto so that the force sensor unit is able to accurately detect the external force.
Priority is claimed on Japanese Patent Application No. 2008-187038, filed Jul. 18, 2008, the contents of which are incorporated herein by reference.
2. Description of Related Art
Among conventional force sensors which detect external force, a force sensor is known which is provided with an attenuator which dampens external force which is applied thereto and then imparts the dampened force to a force sensor chip. This type of force sensor is disclosed in Japanese Unexamined Patent Application, First Publication No. 2003-254843.
This attenuator is provided with a dampening mechanism section which is used to dampen external force which is from an input section where external force is input to the force sensor chip via a transmitting section. Accordingly, external force is not transmitted directly to the force sensor chip.
For example, as disclosed in Japanese Unexamined Patent Application, First Publication No. 2007-010379, the dampening mechanism section of the attenuator is a disc-shaped portion which connects together a shaft-shaped input section and a circular cylinder-shaped sensor fixing section for the force sensor chip. A plurality of arc-shaped holes are provided in a toroidal shape this disc-shaped portion and input section, and by adjusting the size, shape, and number of this plurality of arc-shaped holes, it is possible to adjust the load resistance and adjust the sensitivity towards the respective axial forces, and thus ensure a degree of freedom when designing a force sensor.
In the above-described conventional force sensor, when an output signal from the force sensor is being amplified, a strain resistance element which forms the detection section of the force sensor performs the amplification while including therein signals which have been affected by changes in temperature. Because of this, the problem arises that any discrepancy from the true value is further amplified.